--- OA_place: publisher _id: '10293' abstract: - lang: eng text: "Indirect reciprocity in evolutionary game theory is a prominent mechanism for explaining the evolution of cooperation among unrelated individuals. In contrast to direct reciprocity, which is based on individuals meeting repeatedly, and conditionally cooperating by using their own experiences, indirect reciprocity is based on individuals’ reputations. If a player helps another, this increases the helper’s public standing, benefitting them in the future. This lets cooperation in the population emerge without individuals having to meet more than once. While the two modes of reciprocity are intertwined, they are difficult to compare. Thus, they are usually studied in isolation. Direct reciprocity can maintain cooperation with simple strategies, and is robust against noise even when players do not remember more\r\nthan their partner’s last action. Meanwhile, indirect reciprocity requires its successful strategies, or social norms, to be more complex. Exhaustive search previously identified eight such norms, called the “leading eight”, which excel at maintaining cooperation. However, as the first result of this thesis, we show that the leading eight break down once we remove the fundamental assumption that information is synchronized and public, such that everyone agrees on reputations. Once we consider a more realistic scenario of imperfect information, where reputations are private, and individuals occasionally misinterpret or miss observations, the leading eight do not promote cooperation anymore. Instead, minor initial disagreements can proliferate, fragmenting populations into subgroups. In a next step, we consider ways to mitigate this issue. We first explore whether introducing “generosity” can stabilize cooperation when players use the leading eight strategies in noisy environments. This approach of modifying strategies to include probabilistic elements for coping with errors is known to work well in direct reciprocity. However, as we show here, it fails for the more complex norms of indirect reciprocity. Imperfect information still prevents cooperation from evolving. On the other hand, we succeeded to show in this thesis that modifying the leading eight to use “quantitative assessment”, i.e. tracking reputation scores on a scale beyond good and bad, and making overall judgments of others based on a threshold, is highly successful, even when noise increases in the environment. Cooperation can flourish when reputations\r\nare more nuanced, and players have a broader understanding what it means to be “good.” Finally, we present a single theoretical framework that unites the two modes of reciprocity despite their differences. Within this framework, we identify a novel simple and successful strategy for indirect reciprocity, which can cope with noisy environments and has an analogue in direct reciprocity. We can also analyze decision making when different sources of information are available. Our results help highlight that for sustaining cooperation, already the most simple rules of reciprocity can be sufficient." alternative_title: - ISTA Thesis article_processing_charge: No author: - first_name: Laura full_name: Schmid, Laura id: 38B437DE-F248-11E8-B48F-1D18A9856A87 last_name: Schmid orcid: 0000-0002-6978-7329 citation: ama: Schmid L. Evolution of cooperation via (in)direct reciprocity under imperfect information. 2021. doi:10.15479/at:ista:10293 apa: Schmid, L. (2021). Evolution of cooperation via (in)direct reciprocity under imperfect information. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:10293 chicago: Schmid, Laura. “Evolution of Cooperation via (in)Direct Reciprocity under Imperfect Information.” Institute of Science and Technology Austria, 2021. https://doi.org/10.15479/at:ista:10293. ieee: L. Schmid, “Evolution of cooperation via (in)direct reciprocity under imperfect information,” Institute of Science and Technology Austria, 2021. ista: Schmid L. 2021. Evolution of cooperation via (in)direct reciprocity under imperfect information. Institute of Science and Technology Austria. mla: Schmid, Laura. Evolution of Cooperation via (in)Direct Reciprocity under Imperfect Information. Institute of Science and Technology Austria, 2021, doi:10.15479/at:ista:10293. short: L. Schmid, Evolution of Cooperation via (in)Direct Reciprocity under Imperfect Information, Institute of Science and Technology Austria, 2021. corr_author: '1' date_created: 2021-11-15T17:12:57Z date_published: 2021-11-17T00:00:00Z date_updated: 2026-04-08T07:11:20Z day: '17' ddc: - '519' - '576' degree_awarded: PhD department: - _id: GradSch - _id: KrCh doi: 10.15479/at:ista:10293 ec_funded: 1 file: - access_level: closed checksum: 86a05b430756ca12ae8107b6e6f3c1e5 content_type: application/zip creator: lschmid date_created: 2021-11-18T12:41:46Z date_updated: 2022-12-20T23:30:08Z embargo_to: open_access file_id: '10305' file_name: submission_new.zip file_size: 29703124 relation: source_file - access_level: open_access checksum: d940af042e94660c6b6a7b4f0b184d47 content_type: application/pdf creator: lschmid date_created: 2021-11-18T12:59:15Z date_updated: 2022-12-20T23:30:08Z embargo: 2022-10-18 file_id: '10306' file_name: thesis_new_upload.pdf file_size: 8320985 relation: main_file file_date_updated: 2022-12-20T23:30:08Z has_accepted_license: '1' language: - iso: eng month: '11' oa: 1 oa_version: Published Version page: '171' project: - _id: 2581B60A-B435-11E9-9278-68D0E5697425 call_identifier: FP7 grant_number: '279307' name: 'Quantitative Graph Games: Theory and Applications' - _id: 0599E47C-7A3F-11EA-A408-12923DDC885E call_identifier: H2020 grant_number: '863818' name: 'Formal Methods for Stochastic Models: Algorithms and Applications' - _id: 25F42A32-B435-11E9-9278-68D0E5697425 call_identifier: FWF grant_number: Z211 name: Formal methods for the design and analysis of complex systems - _id: 2584A770-B435-11E9-9278-68D0E5697425 call_identifier: FWF grant_number: P 23499-N23 name: Modern Graph Algorithmic Techniques in Formal Verification - _id: 25832EC2-B435-11E9-9278-68D0E5697425 call_identifier: FWF grant_number: S 11407_N23 name: Rigorous Systems Engineering publication_identifier: issn: - 2663-337X publication_status: published publisher: Institute of Science and Technology Austria related_material: record: - id: '9997' relation: part_of_dissertation status: public - id: '9402' relation: part_of_dissertation status: public - id: '2' relation: part_of_dissertation status: public status: public supervisor: - first_name: Krishnendu full_name: Chatterjee, Krishnendu id: 2E5DCA20-F248-11E8-B48F-1D18A9856A87 last_name: Chatterjee orcid: 0000-0002-4561-241X title: Evolution of cooperation via (in)direct reciprocity under imperfect information type: dissertation user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd year: '2021' ...